The present invention relates to vehicle seats equipped with hinge mechanisms.
More particularly, the invention relates to a vehicle seat having first and second sides, said seat comprising a seat proper and a seat back mounted to pivot relative to the seat proper by means of a hinge mechanism, said hinge mechanism comprising first and second hinges which are disposed on respective ones of the first and second sides of the seat, and each of which comprises:
first and second cheek plates mounted to pivot relative to each other about an axis of rotation that is common to the first and second hinges, the first cheek plates of the first and second hinges both being secured to a first element chosen from the seat proper and the seat back, while the second cheek plates of the first and second hinges are both secured to a second element chosen from the seat proper and the seat back, the second cheek plate of each hinge being permanently secured to or integral with a first set of teeth which extends over at least an arc of a circle centered on the axis of rotation;
at least one slug provided with a second set of teeth suitable for coming into engagement with the first set of teeth, said slug being mounted to move at least radially relative to the first cheek plate between firstly a fully engaged position, in which the second set of teeth meshes fully with the first set of teeth to lock the corresponding hinge, and secondly a maximally separated position, in which the slug does not co-operate with said first set of teeth, and in which the second set of teeth is spaced apart from said first set of teeth to the maximum extent, the slug being mounted to move over a first stroke from its maximally separated position to a limit-of-engagement position in which the second set of teeth is at the limit of the first set of teeth, and said slug being mounted to move over a second stroke from its limit-of-engagement position to its fully engaged position;
a cam mounted to turn about said axis of rotation and suitable for pushing the slug into its engaged position, the cam being mounted to move between a rest position in which said cam places said first slug in its fully engaged position, and an active position in which said cam enables the slug to be placed in its maximally separated position, and said cam being urged resiliently into its rest position in a first angular direction about the axis of rotation, the cams of the first and second hinges being mounted to move over the same angular stroke between their respective rest positions and their respective active positions; and
a control member coupled to the cam and adapted to push the slug into its maximally separated position when the cam is in the active position, and to enable the slug to be placed in its fully engaged position when the cam is in the rest position;
the seat further comprising:
a drive member that can be actuated by the user and that is coupled to a first cam chosen from the cams of the first and second hinges, for moving said first cam from its rest position to its active position, in a second angular direction; and
a lost motion mechanical coupling which, with a certain amount of angular play, connects the first cam to a second cam chosen from the cams of the first and second hinges, and which is adapted to drive the second cam into its active position when the first cam is moved into its active position by the drive member, said mechanical coupling being adapted to enable the first and second cams to find themselves simultaneously in their rest positions.
Document FR-A-2 766 137 describes an example of such a seat.
The seat described in that document is quite satisfactory but does however suffer from the drawback that, because of the tolerances for assembling the structure of the seat, combined with the tolerances for assembling the seat to the floor of the vehicle, and also combined with a small amount of angular play in the first and second hinges, the teeth on the slugs can find themselves in angular positions that differ from one hinge to the other relative to the teeth of the corresponding first set of teeth.
In some cases, that can give rise to the two hinges being prevented from re-locking fully after they have been unlocked, in particular when the angular offset between the teeth on the slugs and the teeth in the first set of teeth is in a first direction in the first hinge and in an opposite second direction in the second hinge. In which case, the two hinges are latched only improperly after re-locking, so that the back of the seat offers only relatively weak resistance to torque that can be exerted on it about its axis of rotation.
Even if they are rare, such situations are dangerous for the user of the seat, particularly (but not exclusively) when the back of the seat carries a seat belt.
An object of the present invention is to mitigate that drawback.
To this end, in the invention, in a seat of the type in question, the second hinge is shaped so that the second set of teeth of said second hinge is in an intermediate position between its limit-of-engagement position and its maximally separated position when the second set of teeth of the first hinge is in its limit-of-engagement position.
By means of these provisions, it is possible for the first set of teeth of the first strength member to engage properly in the corresponding second set of teeth before the first set of teeth of the second strength member starts engaging in the corresponding second set of teeth, which makes it possible to avoid situations in which the first sets of teeth of the two strength members are offset angularly in opposite directions relative to the corresponding second sets of teeth. In addition, even when the second set of teeth of the first strength member remains offset relative to the corresponding first set of teeth, thereby preventing the slug of the second strength member from reaching its fully engaged position, the lost motion coupling nevertheless makes it possible for the slug on the first strength member to reach its fully engaged position.
In all cases, it is therefore certain that at least the first hinge is properly locked when the user releases the actuating member.
In preferred embodiments of the invention, any of the following provisions may optionally be used:
the second hinge is shaped so that the second set of teeth of the first hinge travels over at least one half of its second stroke when the actuating member is moved in a first angular direction far enough for the second set of teeth of the second hinge to go from said intermediate position to its limit-of-engagement position;
at least one of the first and second sets of teeth of the second hinge is constituted by truncated teeth, each of which has a free end forming a flat;
one only of the first and second sets of teeth of the second hinge is constituted by truncated teeth, each of which has a free end forming a flat, the other one of said first and second sets of teeth of the second hinge being constituted by teeth each of which has a free end that is rounded;
the flats formed by the free ends of the truncated teeth are all defined by the same circularly cylindrical surface centered on the axis of rotation;
the set of teeth that has the truncated teeth is the second set of teeth of the second strength member;
the seat is provided with a seat belt connected to the seat back in the vicinity of the first side of the seat;
the first hinge is stronger than the second hinge;
the first hinge is of diameter larger than the second hinge;
the control member of each hinge is a control mask provided with at least one cam edge that comes into abutment against a stud provided on the slug so as to push said slug into its retracted position when the cam of said hinge is in the active position; and
the first cam is the cam of the first hinge, and the second cam is the cam of the second hinge.